docs: Add release note for p224 removal

Signed-off-by: Roland Mikhel <roland.mikhel@arm.com>
Change-Id: I63d8b38e1d7a15fdc20e36daf768ffd26ac6469c
diff --git a/docs/release-notes.d/p224-removal.md b/docs/release-notes.d/p224-removal.md
new file mode 100644
index 0000000..07a5d92
--- /dev/null
+++ b/docs/release-notes.d/p224-removal.md
@@ -0,0 +1 @@
+- Drop ECDSA P224 support